Physical Identification Flashcards
Composition of PI Examiners
Forensic Chemical Officers (FOCOs)
➢Criminologists
are Licensed Chemical Engineer, Chemist and Registered Medical Technologist
Forensic Chemical Officers (FOCOs)
Scope of PID Examinations
- Ultraviolet examination
- Bullet trajectory examination
- Macro etching examination
- Hair and fiber analysis
- Tool marks examination
- Casting and molding examination
- Microscopic paint analysis
- Presence of Inflammable Substance examination (to BFP)
When two objects come in contact with each other there is always an exchange of materials between them.
This type of material exchange – contamination – must be avoided through out the material handling chain, from ______ at the crime scene to the _______ in the laboratory.
collection
examination
__________WE SHOULD COLLECT ANY AND ALL TYPES OF PHYSICAL EVIDENCE.
AS A RULE OF THUMB,
is a principle with broad application that is not intended to be strictly accurate or reliable for every situation.
A rule of thumb
FOUR-WAY LINKAGE THEORY
Physical evidence
Victim
Suspect
Crime Scene
One of the most common types of physical evidence that an investigator and/or crime scene specialist will encounter will be ______
trace evidence.
is a generic term for small, often microscopic material.
Trace evidence
Trace evidence at a crime scene can include _____
blood, hair, fibers, glass particles, paint, soil, etc.
is a means sanctioned by law in ascertaining the truth of any alleged matter of fact.
Evidence –
is that one having objective existence that is, in any dimension, size or shape.
Physical evidence –
is the generic term for evidence that are small, often microscopic materials that may include hairs, fibers, glass particles, foot or tire impression, dust, soil, metal tool marks, tire tracks and paint flakes or chips.
Trace evidence –
is a filament mostly protein that grows from the follicles found in the dermis.
Hair -
is the smallest single unit forming the basis of a textile yarn. A _____ is composed of numerous fibers which are spun, twisted, or drawn together to prepare the unit for weaving or knitting. A yarn is sometimes called a _____ by the layman.
Fiber or filament -
yarn
thread
is a fused mixture of silica, usually in the form of natural sand and two or more alkaline bases such as soda, lime or potash. It also contains quantities of various other element and metals, present as either as incidental impurities in the basic ingredients, or added to them for color, degree of hardness, heat-resistance and other specific purposes.
Glass –
any object capable of making an impression on another object.
Tools –
any impression, cut, abrasion, or gouge (scratch, scrape, hollow, mark, cut into) left by a tool after coming in contact with an object
Tool marks –
determines the point of impact, position of the firearm and the probable caliber of the firearm used.
Bullet Trajectory Examination –
is a liquid suspension in a solvent carrier into which white or colored pigments and a polymeric resin binder have been combined
Paint –
is the application of chemical solution on the metal surface where serial numbers is normally located and observing any reaction that may take place.
Macro-Etching or Acid-Etching -
a series of number that is punched or pressed into a particular item to distinguish it from one another of common type.
Serial Numbers –
is a radiation of shorter wavelength than the radiation commonly recognized as visible light. It is sometimes known as “_______” because of its invisibility to the eye.
UV light –
black light
is a filamentous outgrowth of dead cells from the skin found only on mammals
Hair
Hair uses _____for morphology and microscopic features in the analysis.
comparison microscope or SEM-EDS
Purpose of hair examination
- To determine whether the hair in questioned originated from an animal or human being and the comparison of questioned and known hairs.
- To ascertain whether one or more individuals could have come into contact with an object.
EVIDENTIARY VALUE OF HAIR
- The value of hair as evidence in the criminal cases has been _______
- It is __________ as evidence, but in conjunction with other details, has proven to be an important and essential aid to the investigator.
clearly recognized.
seldom conclusive
origin can be of fine to medium coarseness, are generally straight or wavy in appearance, and exhibit colors ranging from blonde to brown black. The hair shafts of _____ vary from round to oval in cross section and have fine to medium-sized, evenly distributed pigment granules
Hairs of Caucasian
Caucasian hairs
origin are regularly coarse, straight, and circular in cross section, with a wider diameter than the hairs of the other racial groups. The outer layer of the hair, the cuticle, is usually significantly thicker than the cuticle of the Negroid and Caucasian hairs and the medulla, or central canal is continuous and wide. ______ hair can have a characteristic reddish appearance as a product of its pigment
Hairs of mongoloid or Asian
Mongoloid
origin are regularly curly or kinky, have a flattened cross section, and can appear curly, wavy, or coiled. _______ are larger than those found in Mongoloid and Caucasian hair and are grouped in clumps of different sizes and shapes.
Hairs of Negroid or African
Negroid pigment granules
Three parts of hair
Root bulb
Hair shaft
Tip
the shape of the root bulb will determine if the hair was pulled by force or not.
Root bulb-
contains the most information about the hair.
Hair shaft –
will show if the hair is cut, burned or if it has split ends
Tip –
Three parts of the hair shaft
Cuticle
Medulla
Cortex
is the outer surface of the hair and when viewed under a microscope appears to be composed of scale like flakes, each overlapping the others like the scale of a fish.
Cuticle –
is the central canal of the hair shaft. It could be continuous, fragmented, interrupted or absent.
Medulla –
contains the color pigmentation of the hair.
Cortex –
________hairs, such as a head hair dislodged through combing, display undamaged, club-shaped
roots.
Naturally shed hair
A hair _______from the scalp will exhibit stretching and damage to
the root area.
forcibly removed
The equipment can be used effectively for examination in various fields of forensics especially related to biological and other trace evidence like gun shot residue, metal, paints, and hair samples.
SEM-EDX/EDS
Scanning Electron Microscope (SEM)
with Energy Dispersive X-ray Spectrometer (EDX) or (EDS)
SEM
IMAGE FORMATION
1.____________ – surface features of an object
2.____________ – shape and size of the particles making up the object
Topography
Morphology
1000 – 1,500 X
(Image Display of hair)
MAGNIFICATION
The most difficult task faced by crime scene specialist is to initially locate ____ evidence at the crime scene. The search for ____ at the crime scene must be thorough, detailed and exact.
Other areas to search include the following:
Victim’s body (especially in sex crimes) _____________ and any upholstered surfaces such furniture and car seats.
Searching for Hair:
hair
hair
underneath the fingernails
Collection of Hair
•Hair discovered at the crime scene should be carefully removed or pick with the use of _________;
- It should be placed in a clean container, such as a ________ which should then be folded and sealed in larger envelopes. Care should be taken during folding to avoid ____ the hair. Label the outer sealed envelope.
- If a pill box is used, the entire length of the hair is in the box and it is not crushed when the lid is put on;
- If hair is attached , such as in dry blood, or caught in metal or a crack of glass, do not attempt to remove it, but rather leave hair intact on the object. If the object is small, mark it, wrap it, and seal it in an envelope. If the object is large, wrap the area containing the hair in paper to prevent loss of hairs during shipment.
fingers or a pair of tweezers
pill box, paper bindles or coin envelopes
kinking
determines the particular tool used in forcible entry or exit in the commission of a crime. Comparing tool marks of crime impression from the crime scene with the suspected tool found in possession of the suspect.
Tool Marks examination
_______ comparison of tool marks
from the crime scene and photographs.
Microscopic
To restore different types of impressions such as shoe prints, foot prints and tire marks at the crime scene.
Since criminals must either walk or drive to and/or from the crime scene, it should be reasonably assumed that traces of impression evidence will be ______
Tool marks
left behind.
Striations from manufacturing process
Defect from use
Striations left on surface
Tool marks
To compare the alleged tool used in committing the crime and the standard tool mark and to compare each mark based on the characteristic striations.
Tool marks examination
The crime scene specialist should make a conscientious effort to thoroughly examine the scene of a crime to determine if any ______were left by the perpetrator. It is also important for the crime scene that may have been left behind. If pieces are located, they must be recovered since they can become valuable evidence when the tool and suspect are located.
SEARCHING FOR TOOL AND TOOL MARKS
•1. Searching for Tool marks –
tool marks
Crime Scene Specialists should ensure that they look in the following areas for potential tool marks:
Doors Windows Safes Drawers of desks Wire fences exhibiting cuts Cut locks
•1. Doors- around the locking mechanisms, paying attention to the wood of the doorframe and jamb.
•2. Windows- on the bottom edge of the window, the sill and framework of the window jamb.
3. Safes-all around the door, locking mechanism and hinges.
•4. Drawers of desks, filing cabinets, or other secured drawers- Pay particular attention to the area around any locks, as well as the joining edges of each.
•5. Wire fences exhibiting cuts- compression marks from the cutting devise are often quite noticeable.
•6. Cut locks- brass locks are particularly good at retaining compression marks from the cutting tool due to the soft nature of the metal.
1
COLLECTING TOOL MARK EVIDENCE
Photography
Original State
Casting toolmarks
Before any attempt to collect toolmark evidence, it should be _____ first in its original state.
It is crucial that the toolmark is permanently recorded before any attempt is made to _______
- Photography-
photograph
replicate or recover.